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opey454 03-25-2013 12:56 PM

Basement Bathroom Plumbing Challenge
4 Attachment(s)
This is my first forum thread as well as my first major plumbing project so between the two I hope to survive and maybe learn a little! I am building a full bath in the lowest level of a 1972 split level home. I am adding a toilet, sink, shower, and utility sink. I am using a 3" ABS pipe for the main toilet drain and a 2" drain for the sink, shower, and utility sink. See the pics for the basic setup (underlined p = p-trap). I had to split the pictures into three due to the size. All apologies for the constant change in direction with the pics. The Sketch is not even close to scale ;) I have sufficient fall from the closet flange of the toilet to the soil stack (approx. 16" over 12 ft length). I plan to use an AAV on 2" ABS pipe built into the new wall (with an access cover) to serve as a wet vent for both the sink and the toilet. I think I need to add another AAV after the utility sink the washer dumps into. I am thinking that pressure from flushing the upstairs toilet may cause siphoning from the new p traps nearby. Another vent maybe helpful with the utility and shower p traps being so close to the 3" vertical soil stack. I have read that AAV's are not always ideal but they seem to be the most logical solution for this setup. AAV's are allowed by my state plumbing codes. Also while I have the floor broke up I am tying the air conditioning condensation drain line into the floor drain. In addition to general feedback, below are some questions I have

1. Are there any major red flags I am missing?
2. Is it ok to have the sink, shower, and utility sink tie into the 3" drain from the toilet?
3. Is there a better idea for the venting?
4. Is there an issue with tying air conditioning condensation drain line into the floor drain?

Thanks in advance for any input

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oh'mike 03-25-2013 05:39 PM

I'll wait until a licensed plumber chimes in----

Here your plans would not pass---a vent must be located within 5 feet of a fixture---

AAVs can not be used to vent a toilet.

Let's see what an experienced plumber has to say---the codes in my area are really tough.

opey454 03-25-2013 06:34 PM

Thanks for your reply. I see what you are saying about the 5 ft. I believe I read in the jumble of my local codes that a toilet in a remodeled basement does not need its individual vent. A friend of mine is a licensed plumber and he said it is no issue using the lav vent for the toilet as well. I am waiting for him to have a chance to look over the rest of the plans for the system. I have debated putting another AAV prior to the shower to serve as the vent for the shower p trap as the basement toilet drains past it. That will also ensure there is a vent at least 5 feet from each trap in the system (minus the toilet which uses the sink drain line as the vent).

oh'mike 03-25-2013 07:08 PM

What he may have been referring to is using the main stack as a wet vent for the toilet---

Why have you chosen AAVs instead of a piped vent?

Ghostmaker 03-25-2013 07:35 PM

You cannot use a stack as a vent. A stack carries waste a vent carries air.

What code is used by your state. What state do you reside in?

opey454 03-25-2013 08:18 PM

I live in ohio. Not using the stack as a vent makes sense. I chose the AAV in order to not vent through the side of the house or through the walls up to the roof. NEWEST UPDATE...My plumber friend admits his advice will make it work but not necessarily "code". He believes the AAV from the lav (on 2" abs) should be enough to vent the whole line. The p-trap for the shower and utility sink will sit almost directly under the 3" drain from the toilet that drops 16" over a 12' run. He did mention maybe to be safer than sorry adding a vent for the shower on the trap arm before it connect into the 3"drain but I may not have the room to do that. We could also tie into the 3" drain with 2" and run a vent from just prior to the san-T for the shower. But he believes in his experience the lav vent will work fine...worst case a slow drain or small gurgle in toilet. Which for self made additional bathroom in the basement is a tradeoff worth considering.

oh'mike 03-25-2013 09:00 PM

Come on plumbers--help me out here----

We can't use AAVs here at all ,so I'm out of my depth on this one------------

jaydevries 03-25-2013 09:12 PM

i agree with what his plumber buddy said but if you can not put an aav on shower i would at least put one at and above wash tub
and toilet will not gurgle it is wet vented off of lav sink but shower might but not likely

TheEplumber 03-25-2013 09:26 PM


Originally Posted by oh'mike (Post 1145822)
Come on plumbers--help me out here----

We can't use AAVs here at all ,so I'm out of my depth on this one------------

I'm UPC- I vent eveything:yes:
To the OP- A slow drain or a gurgle is not a trade off worth considering :no:

Ghostmaker 03-26-2013 07:36 PM

Bad luck for you I'm an Ohio plumbing inspector..... LOL

What your proposing to do will not work properly.

Is there any other fixture in the basement that has a vent? Otherwise you can no longer use an AAV in your situation.

You will need to vent the lav sink and you need to vent the washer

No other vents are required
Run 3 inch to the washer then bush it down to 2 inch once you turn up.

Run 1 1/2 to your lav

Run 2 inch to your shower trap

Install a pressure balanced temperature control shower valve with integral stops on H and C feeds.

Get a permit if required so house does not get condemned.... In truth what may happen is code authorities may catch you and you get to rip all your stuff back out. WHat has happened is I was hired to look at a house that a buyer was looking at and found it was plumbed without permit and improperly vented. I had to inform the potential buyer... Your house is your greatest investment so treat it like it is.

oh'mike 03-26-2013 09:04 PM

Ghost---In this area the smallest drain that can be buried is 2 inch--Is 1 1/2" allowed under a slab in Ohio?

TheEplumber 03-26-2013 09:16 PM


Originally Posted by oh'mike (Post 1146548)
Ghost---In this area the smallest drain that can be buried is 2 inch--Is 1 1/2" allowed under a slab in Ohio?

Mike, its funny you ask this. Twenty minutes down the interstate from me is Washington. I can run 1.5" under slab all day long there. But when I come back to Idaho- minimum is 2". Both states use UPC with local amendments Oh, and I can use a lot more AAV's in Washington. Idaho only allows them on residential islands or remote locations when remodeling a home(as of 2012)

jaydevries 03-26-2013 09:28 PM

917.7 Vent required. Within each plumbing system, a minimum of one stack vent or vent stack shall extend outdoors to the open air.

umm correct me if i am wrong but i am pretty sure there is one vent extended outdoor on the vertical stack that he is tying into so that would allow him to use an aav

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